New York -LRB- CNN -RRB- -- After a sudden increase in shootings over the weekend , the New York Police Department has deployed more officers , NYPD Deputy Commissioner Paul Browne said .

More uniformed officers will be assigned to public housing developments citywide , and plainclothes officers will go to borough - and precinct-based anti-crime units during hours that are prone to shootings .

As weekend temperatures topped 90 degrees Fahrenheit , New York City saw a sudden increase in shootings , with 26 people felled by bullets in 72 hours -- seven fatally . Three of the injured victims were younger than 16 , Browne said .

`` When we have hot temperatures , we see that the crime rate seems to go up , '' New York City Mayor Michael Bloomberg said Monday .

Investigators are also monitoring gangs for any signs of planned retribution based on shootings over the weekend , Browne said .

Mobile and fixed camera-equipped observation towers will also be used near the sites of the recent shootings , Browne said in a statement .

But even after the shootings in the 72-hour period from Friday through Sunday , Bloomberg emphasized that the year 's homicides are down 24 % from last year , for a total of 127 through Sunday , which is 40 less than the same period in 2012 .

`` One shooting is one too many , but last week we had the fewest shootings in a decade , including this weekend 's shootings , '' Bloomberg said .

In November 2012 , New York City logged a record-breaking `` murder-free Monday , '' when there was not a single reported slaying , stabbing or shooting in any of the five boroughs , the New York Police Department said .

`` It is unusual in a city of 8 million people , but we never read that much into one day , '' said Browne , who said it was the `` first time in memory '' that the city had such a lull in violent crime .

At the close of 2012 , Bloomberg called New York City the `` safest big city in America , '' giving the NYPD credit .

`` The fact that the safest big city in America is safer than ever is a testament to the hard work and determination of the men and women who put their lives on the line for us every day -- and it also reflects our commitment to doing everything possible to stop gun violence , '' he said .

CNN 's Laura Ly contributed to this report .

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In New York , 26 people were reported shot in a 72-hour period from Friday to Sunday

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More officers will go to public housing and anti-crime units

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Investigators are also monitoring gangs for any signs of planned retribution